American Institute of Certified Planners (AICP) Practice Exam

Principal arterials are designed to facilitate the movement of large volumes of traffic over longer distances and typically connect major destinations within urban areas. As a result, they carry a significant amount of vehicle miles traveled (VMT) because they serve both local and through traffic, making them crucial for regional connectivity. The design and function of principal arterials prioritize efficiency and speed, allowing them to handle high traffic volumes effectively.

In contrast, local streets primarily serve to provide access to individual properties and neighborhoods, which results in a lower percentage of VMT compared to principal arterials. Collectors serve as a transition between local streets and arterials, but they do not accumulate as much traffic as principal arterials do. Minor arterials also provide important connections but typically carry less volume than principal arterials due to their role in connecting smaller communities or neighborhoods rather than serving as major thoroughfares. Therefore, principal arterials, with their extensive reach and focus on facilitating longer trips, are responsible for the highest percentage of VMT among the roadway categories listed.